Pressure gauge



April 5, 1949. c. WANTZ vET AL PRESSURE GAUGE Filed May 20', 1944 U. mw @W WW .MR WW Wm 1H .w H

Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE PRESSURE GAUGE Application May 20, 1944, Serial No. 536,510 6 Claims. (Cl. 73 411) This invention relates to improvements in pressure gages.

Accurate calibration of pressure gages is obtained by adjusting the rate of movement of the indicator hand relative to the movement of the manometer or pressure responsive element. Adjustment of the initial relative position between plished by manually bending and permanently distorting metal connecting linkage and lever arms comprising the motion transmission means of the device. However, speed and accuracy of calibration are diicult to obtain in this way.

One of the objects of this invention is, therefore, to provide a pressure gage which may be easily, quickly and accurately calibrated, without distortion of the working parts.

Another object of the invention is to provide a pressure gage in which back lash and lost motion in the motion transmission means is eliminated or reduced to a minimum.

A further object of the invention is to provide a pressure gage which may be readily constructed from machine parts.

The foregoing objects are accomplished by providing a connection between the pressure responsive device and the pivotally mounted indicator hand which will keep the working surfaces under pressure contact while the parts are in motion thereby eliminating back lash and lost motion, and including a frictionally maintained relatively movable element to vary the distance between the pivotal axis of the hand and said connection. The position of said element can be quickly and accurately regulated to make small adjustments in the length of the lever arm by which the motion of the pressure responsive device is transmitted to the indicator hand. The indicator hand is also provided with an oiset portion between the hub and finger. This oifset portion is of such proportion that it may be easily deformed to make suilicient changes between the relative positions of the hub and the nger to obtain a zero setting.

With the foregoing and other objects in view, developed by the following decription, the invention consists in certain novel advantageous structural organizations and features, as well as combinations and sub-combinations, as more fully explained hereinafter and specied by the following claims. y

Referring to the accompanying drawings forming a part hereof,

Figure 1 is a top plan view of a pressure gage comprising the invention;

Figure 2 is a fragmentary, greatly enlarged top plan view of the pivotally mounted eccentric sleeve, hub portion of the indicator hand, and the wire link connecting the end of the Bourbon tube and the hub of the indicator hand;

Figure 3 is a fragmentary View in side elevation taken from the line 3 3 of Figure 2 Figure 4 is a sectional view taken on line 4 4 of Figure 2;

Figure 5 is a sectional view taken on line 5 5 of Figure 1;

Figure 6 is a view partly in section and partly in side elevation of the eccentric sleeve comprising a part of the mounting for the indicator hand; and

Figure 7 is a top plan view of the accentric vsleeve of Figure 6.

Referring in greater detail to the drawings, there is illustrated a pressure gage embodying the invention. In general, the pressure gage comprises the following elements: a body I 0 on which the other elements are mounted; a Bourbon tube 20, the free end lof which has limited motion under the iniluence of changes in pressure in the pressure to be measured; an indicator hand 30 which tially lineal motion of the free end of the Bourbon tube 20 to the indicator hand 30 at a point removed from its pivotal axis to cause it to have angular movement; a dial 60, provided with a scale` over which the nger of the indicator hand 30 travels to indicate selected pressures of the pressure being gaged; and a cover member 'I0 having a sight window enclosing the working parts.

The construction of the body member I0 is such that it may be readily fabricated as a machine part rather than a casting. The main portion has depending centrally therefrom a threaded nipple II. The nipple II is adapted to lit in standard fittings customarily used in connecting pressure gages to the pressure tok be gaged. Also centrally located with respect to the main portion is an upwardly projecting cylindrical boss I2. The boss I2 and nipple I I are axially aligned, and a drilled out passageway I3 extends along their axis from the bottom of the nipple I I to approxiageway I3 to the outer side of the boss I 2. The fpassageway I4 is lprovided with a counter-bore 'endlof the tube .that small changes in `lever arm will cause the flnger3| `to vary its rate I5 for receiving and holding the tubularly shaped end of the Bourbon tube 20. A flange I6 extends around the periphery of the main portion to form a lip for engaging the cover member 10 to retain it in proper position. The main portion is also provided with` al drilled hole l1? which receives and holds the pivot pin 4| upon which the eccentric sleeve 4U pivots, and a tapped hole I8 intoV which a screw may be threaded to hold the cover 10 in place. It should be noted that the body member |0 is preferably turned from hexagonal stock which permits the mainA portionto also act' as a nut by which the entire curely threaded into place. However, it may be cast instead of turned and any irregular shape may be conveniently used tolprovide a gripping.

the confines of the tube and is provided witha notch in link -50 mayrest and be held during the application and solidifying of the solder 2G", orother material or method used to rigidly join-the clip24'and wire linkv 50.

The-movement of the freeend of the tube 20 under changes in pressure is relatively small, andK it cannot readily bevisually distinguished. It is, therefore, necessary to provideV an indicator hand 3|),v the nger 3| of which hasYa-rangeof movement considerably greater` thanthe move- 4ment ofl the free end of the tube. The dial` 60 with its-scaleof selected pressures is securedto thelface Vofthe boss-|2'insuch a manner that the scale andthe tip ofthe finger 3|` are irl-register as theindic'ator hand swings from one endl of the-scale tothe other as thezpressure to be meas*- ured increases from a selected low` limit to a vselected high limit.

To accomplish such cator hand 3l] is 20is connected to .the .hand at a pointnear `the pivotalaxis-ofzthe hand (pivot4l) byV the Vwire link 50. Thus.y small substantially linealmovement ofthe freeendfof thetube 21| acts .through alrelatively shortrleverV armato cause the finger 3|' to'l have relatively; large angular or swinging movement. It will be seen, therefore, thelength` of the small swinging'motion, the vindi-- respect, to theA movement of the free end of the tube. This fact is utilized to eiect acalibration. of thegage inthe final testing stepof manufacture.,

Therefore, themeansforr pivotally mounting the indicator hand. 30 also', includesY meansfor of 1 i movement with .makingsmalladjustments in the length of the small lever arm., The. pivotpin 4|, which.has a drivet-in the drilled hole` |,1provides theaxis of the pivotal mounting` An eccentrically formed sleeve 40 rotatably fits on the. p in 4|.- This detail in Figures ,6 and 7), is from hexagonalistock. It has sleeve` (shown in preferably formed a,lower1p ortion 42.which isL turned down concentric with the longitudinal.Y axis of the-stock.4 An

intermediate portion 44 is not turned down and location of the boss |2with pivotally mounted and the free r gage may be seretains its hexagonal shape to form a nut by which the sleeve may be held for purposes of making adjustments. Immediately above the nut portion 44 there is a cylindrical spacer 45, the longitudinal axis of which is offset from the longitudinal axis of the stock. This spacer carries cylindrical support-46 for the indicator hand 30. The longitudinal axis of the cylindrical support 46 is also offset from the longitudinal axis of thefstock. The sleeve 40 is provided with a longitudinal bore 43 co-axial with the axis of the stock. This bore provides a bearing between the sleeve 4|)l and shaft 4| by which the sleeve is rotatively mounted on the body l0. The indicator hand 3Uhas a hub 32 provided with a bore into whichl thecylindrical support 46 tightly fits. The bottom of the hub rests against the shoulder formed by the juncture between the spacer 45 and the cylindrical support 4S. In order to thusly hold'tliehub32; theperimeter ofthe top surface of the cylindrical support 46 is swaged over the hub '32.2 Thetool for; such swaging may be guided bythe stud41`, formedon the cylindrical support 46; Thefitv between the cylindrical support 4i and the bore of hub 32ris sucientlyA tight to cause the hub andthe sleeve to rotate as a` unit about thepivot pin14l. However, ifthe hub 32 is held, the sleeve 40fmaybe rotated relative thereto by exerting sufficient rotative pressure on the nut 44. The-hub 32 isialsoi provided-with an aperture 34 forrotatively receiving the down-turned end of the wire link Sunto. form motion transmission means therebetwee The distance betweenthe center ofthe aperture 34 and the axis of the pivot.` pin 4| constitutes the length of thesmall lever. arm;heretofl discussed. A- nger 3|: is con-.- nected to the hub 32 byanoffsetportionl33. The offset portion 33 issulciently long to permitrit to bereadily twisted. to. effect zeroadjustment.

r The transmission ofy motion from the Bourdon tube 2li; to; they indicator. handl 30.,is vaccomplished by a wire link 5|).which. has av turnedfdown por.- tion,-5.| rotativelyvflttingwithinthe aperture 34. The turned-down portion. 5| is of suiiicientlength so that when its endfrestsagainstthe upper. sur.- face'of; the nut` portion;44; the, curved portion between'the main body of the'linkY and the down'- turned .portionSIrwillbe held outof engagement with the;aperture,3,4thus preventing, the possibilityv of friction.v or binding action between the hub 32-and the link 5|).- As is shownin Figures 2, Sande, thewire link vlill vhas its other, end loosely resting ,in a ,notch :2 5 Vformediin theclip. 24. After proper adjnstmentshave been made during the assembly ofthe device, this end ofthe linkis rigidly anchored inplacein theclip 24.

A cover orhousing lllts overthe working parts ofthe gage; It comprises aninverted metal` cupshaped merriberfthe` skirts or. sides of whichfit `withintheflange||l `One-half ofthe topof the cover I0-is preferablyY cut away, to providea `window substantially, in; registry with the dialL 60. A sheet of transparentmaterial 1| is fitted/with the cover toclose ,theopeningor cutawayportion. This sheet is held in place by a smaller inverted cup-shapedholding member 12 telescoped within the coverA 'HlY and held inI place by apressure flt orother known means. A screw 13 p asses through holes in the .top ofpthe cover 1|) and holdingmember` 12 ,andthreadsintouthe;tapped hole IB. `A spacer J4 isipositioned over andiheld on the-screw to prevent undue distortion of the Atop of ythe cover l0 andto.prevent-disassembly of the screw from the cover when the cover has `beenremoved.

After the gage has been assembled, with the exception of rigidly securing the link 50 to the clip 25,

tension is removed, tinually has the effect of maintaining the bearing surfaces between the pivot pin 4l and the sleeve as one unit, and the aperture 34 and the downturned portion 5| as another unit, in close surfaceto-surface contact. Slight tension may be also Even if the wire is not so making the rigid connection, an is still obtained by the step of making the rigid connection after the wire has been loosely assembled in place. This result is the insurance of a connection having minimum frictional losses. This is accomplished because the turn-down portion 5| of the wire link 50 is properly alined in the aperture 34 by the action of the close tolerance t therebetween, and this proper alinement is not thereafter disturbed by subsequently rigidly anchoring the link to the tube 20,

The Bourdon tube is next subjected successively to increasing known pressures. As the tube expands from one known pressure to another, the resultant movement of the finger 3| should be such as to move it the same distance as exists between those markings on the scale of the dial which corresponds with such known pressures. If this does not occur, it is necessary to adjust the rate of movement of the indicator hand 30 to the rate of movement of the free end of the Bourdon tube 2U. In this device such correlation is eifected by increasing or decreasing the distance between the longitudinal axis of the pivot pin 4| and the center of the aperture 34, heretofore described as the relatively short lever arm by which the lineal movement of the link 50 is translated to angular movement of the indicator hand 3U. As the cylindrical support 46, upon which is carried the hub 32, is eccentric to the axis of the pivot pin 4|, relative rotation between the hub 32 tween the parts. deected prior to important result and the sleeve 40 causes the length of such lever arm to vary in relatively small amounts. If the distance moved by the finger is too short, the

lever arm mustbe decreased to increase the rate of movement. If such distance is too long, the lever arm is increased in length. To accomplish this relative movement, the hub 32 is held while the sleeve is rotated relatively thereto by applying turning pressure on the nut 4 bration.

Although there is shown and described certain specific embodiments of the invention, many modicati'ons thereof are possible. The invention is not to be restricted except insofar as necessitated bythe prior art and by the spirit of the appended claims. f

We claim:

1. In a pressure gage, a pressure responsive device having a portion movable under the influence of changes in pressure to be gaged, a pivotally mounted sleeve provided with an eccentrically positioned support, an element of an indicator mechanism provided with a hub, said hub being frictionally engaged by said support whereby said sleeve and indicator element normally pivot just the to the movement of said pressure responsive device.

2. In a pressure gage, a Bourdon tube, one end of which is movable under influence of pressure to be gaged, a clip on said end having a slot adapted to Ireceive and loosely hold one end of a lwire link, a pivotally mounted indicator hand having a hub provided with an aperture to receive another end of a wire link, and a Wire link having one end rotatively engaged in said aperture and the other end positioned in said slot, said last mentioned end being held in said slot by solder which has solidified after said wire link has been deflected from its normal position,

stresses all bearing and lost motion.

3. In a pressure gage, a pressure responsive element movable under the inuence of changes in the pressure to be gaged, a pivotally mounted member provided with an eccentrically positioned hub receiving support, an indicator hand having a hub, said hub being frictionally engaged by said support, whereby said member and hand normally pivot as a unit, a laterally distorted and pre-tensioned wire link connecting said pressure responsive element and said hub whereby the motion of said element causes said sleeve and hand to pivot as a unit, said link by reason of its prestress causing all relatively movable connecting and bearing surfaces to remain in close contact to eliminate back lash and lost motion, said hub and said support being relatively adjustable to vary the distance between the point" of connection of said link with said hub and the axis of pivotal movement of said pivote-ily: mounted member.

4.Ina pressure gage, a Bourdon tube,4 one. end or which.y is movable under influence of `pressure tabegaged, a clip onsaid end. havingv a. slot adapted to receive and loosely-hold oneI en of awire link, a pivotally mounted indicator hand having a hub provided with an aprtureto receive another end of a wire link, ,and a wire link havngone end rotatively engaged in said aperture and the other end positioned in said slot,4 said lasttmentioned end being rigidly secured in said slotwhile said wire is deflected from. its normal position,` whereby said Wire link. acts to convey motionfrom said tube to` said indicator andalso prestresses all bearing surfaces to preventback lash` and lost motion.

5; In a pressuregage, a'Bourdon tube, aneccentric freely pivotally mounted adjacent said tube, an indicator hand havinga hub portion frictionally` mounted on said eccentric, saidhub portion and said eccentric constituting a crank arm, and a direct connection betweenthe latter and the freev end of said. tube, movement` of said eccentric relative tosaidhub vportion-varyf,

length of said crankI arm and hand relative to ing` the effective theF rate of movement or said that of said tube.

6. In a pressure gage, a Bourdon tube oneend of which is movable under influence o changes to begaged, an element of anfindi- .mounted `to y permit swinging thereofin the actuationof. theindicator mechanism, a wire link retaining element on said movable end oi said tube, a circular bear,- ing aperture in said indicator mechanism element for rotatively receiving a laterally projecting portion of a connecting link, a, wire link having one CLAR RICHARD K. ENGHOIDT.

REFERENCES CITED The. following references are of recordvin the flleoi this patent:

n' UNITED STATES PATENTS Number Name Date 987,039 Blanchard et al. Mar. 14, 1911 1,315,327 Place Sept. 9, 1919 5 1,345,630- Placel July 6,11920 l';510,193 Pryor, Jr Sept. 30, 1924 1,666,556 Cravn Api'. 1'7, 1928 1,857,139 CarltonA May 10, 1932 1,904,492 Manuel Apr. 18, 1933 ,f90 1,978,750 Klein Oct. 30, 1934 2,247,102 Sugden et al June 24, 1941 A 2,332,103 Mather Oct. 19, 1943 FOREIGNV PATENTS ,et Number Country, Date 355,358 France Aug. 26, 1905 752,391 France Julyl'?, 1933 guiding action of 

